Heats of combustion of graphite carbon and carbon monoxide are respectively `- 393.5 kJ mol^(-1)` and `- 283 kJ mol^(-1)`. Calculate the heat of formation of carbon monoxide. 

Explanation

`C_(("graphite")) + O_(2(g)) to CO_(2(g)) , DeltaH = -393.5 kJ "   " …(1)`
`CO_((g)) + 1/2O_(2(g)) to CO_(2(g)) , DeltaH = -283kJ "    "....(2)`
Equation (1) - Equation (2), gives
`C_(("graphite")) + 1/2O_(2(g)) to CO_((g)), DeltaH = -110.5 kJ`.